S 63 AMG ”Thirty-Five” meets 300 SEL 6.8 AMG

A comparison between generations of a special kind

Spa-Francorchamps (Belgium) – Wide, spectacular and clad in an authentic racing car outfit – two very special S-Class saloon models from the AMG stable. One is the racing touring car of 1971, the 300 SEL 6.8 AMG, and the other is the S 63 AMG showcar. With identical sponsoring and the memorable start number “35,” the new high-performance model is a reminder of an historic success: on 25 July 1971, the bright red four-door saloon crossed the finishing line in second place at the 24-hour race in Spa-Francorchamps. This triumph in the car’s very first race made AMG world-famous overnight.

The highly experienced Hans Heyer and Clemens Schickentanz took turns behind the wheel of the AMG touring car. AMG was anything but the favourite to win this classic Belgian long-distance race: it faced the mighty opposition of the Ford Capri RS, BMW 2800 CS, Chevrolet Camaro, Opel Commodore and Alfa Romeo GTA. Nobody expected that the large luxury saloon from Affalterbach in provincial Swabia would be able to keep up with the well-established teams.

5th place in the starting line-up for AMG

The red four-door saloon already showed its potential in training, when Clemens Schickentanz surprised everyone with the fifth-fastest training time. Indeed nobody at AMG had expected fifth place in a starting line-up of 60 cars. 80,000 spectators wondered about the fast, red saloon with its long wheelbase – the only Mercedes taking part in the race. Pole position was occupied by the favourite, the Chevrolet Camaro driven by Ivo Grauls and Peter Hoffmann, followed by the Alpina-BMW 2800 CS of Niki Lauda/Gérard Larousse, then the first works Ford Capri with Dieter Glemser and Alex Soler-Roig, and the Schnitzer-BMW 2800 CS piloted by Rauno Aaltonen and Helmut Kelleners. All in all, 60 racing touring cars were seeking to beat the stopwatch on the then 14.1 km course in the Ardennes, driven by well-known names such as Hans-Joachim-Stuck, Jochen Mass, Toine Hezemans, Willy Kauhsen, Achim Warmbold and Rainer Braun.

On the first lap, driver Hans Heyer in the 300 SEL 6.8 AMG was able to manoeuvre into 3rd place right behind the Ford Capri (Glemser/Soler-Roig) and the Chevrolet Camaro (Grauls/Hoffmann). After a turbulent race with a rainstorm at midnight and numerous breakdowns, the “35” finally crossed the finishing line in second place behind the works Capri driven by Glemser/Soler-Roig. The AMG saloon had absolved exactly 308 laps in the 24 hours. Technical problems: none at all. A sensational result.

Top speed of 265 km/h (165 mph), and exotic wood trim in the cockpit

Hans Heyer looks back fondly on this race: “We knew we could win, but the others did not know that yet!” The AMG saloon was unbeatable on the straight, however the braking system substantially adopted from the standard model had problems coping with the weight of the car (1635 kilograms, 3604 lbs). “But on the old Spa course the discs had plenty of time to cool down, and nobody was able to catch us on the long straights,” the now 67 year-old reminisces. With a top speed of 265 km/h (165 mph), the 300 SEL 6.8 AMG was tailor-made for the fast Belgian track. The interior had a luxurious atmosphere with its standard appointments such as power steering, air suspension, carpets, panelled doors and a dashboard with exotic wood trim. The spectators along the trackside enthusiastically cheered the large saloon with its unmistakable V8 sound. “The outsider quickly became the public’s favourite,” says Hans Heyer.

The AMG racing saloon was technically based on the Mercedes-Benz 300 SEL 6.3. With an engine output of 184 kW (250 hp) at 4000 rpm and a top speed of 220 km/h (137 mph), this luxury saloon was Germany’s fastest regular production car at the time. It was not only an enlarged displacement from 6330 to 6835 cc that increased the output to 315 kW (428 hp) at 5500 rpm, and torque from 500 (368 lb-ft) to 608 Nm (448 lb-ft). AMG co-founder Erhard Melcher “tweaked” the eight-cylinder power unit using classic methods: high-precision camshafts and modified rocker arms, lighter connecting rods, new Mahle pistons, larger intake valves, modified combustion chambers, polished intake and exhaust ducts, a new intake tract with two throttle flaps and a racing exhaust system ensured a better gas throughflow and made higher engine speeds possible. Endurance was improved by installing an additional oil cooler and finely balancing the crankshaft.

300 SEL 6.8 AMG engine

The wings were flared to make room for the lightweight size 10 x 15 and 12 x 15-inch magnesium wheels adopted from a C 111 test car. Aluminium doors helped to reduce the car’s weight from the original 1830 to 1635 kilograms (4034 to 3604 lbs). Larger front wishbones, a more robust rear axle with a heavy-duty differential and smaller, stiffer suspension air bellows made the saloon fit for the racetrack.

Sensational success reported on German TV news

300 SEL 6.8 AMG at the 24-hour race in Spa-Francorchamps, 1971

The unexpected success in the 24-hour race at Spa-Francorchamps made AMG, which was founded in 1967, well-known overnight – and marked the start of an impressive success story. Even the German TV news “Tagesschau” reported on this sensational result. “It really was a sensation at the time,” AMG founder Hans Werner Aufrecht remembers. The courage shown by Aufrecht and his partner Melcher in entering such a car in the classic 24-hour race had been well rewarded.

Afterwards the 300 SEL 6.8 AMG took part in the 2×6 hour race at Paul Ricard on 11 and 12 September 1971, accompanied by a privately entered 300 SEL 6.3 with an AMG engine. In March 1972, now repainted in yellow, the 300 SEL 6.8 AMG took part in the trials for the Le Mans 24-hour race, but did not take to the starting line for the June race. The car was however entered in the 24-hour race at the Nürburgring in June 1972, and in the Nuremberg 200-mile race at the Norisring on 6 August 1972, where Hans Heyer took first place in the “Standard and special touring cars above 2000 cc” category with the four-door saloon, which had meanwhile been painted red again.

The success story of the 300 SEL 6.8 AMG came to an end there: a rule-change by the Fédération Internationale de l’Automobile (FIA) put the brakes on this muscular racer, as only cars with an engine displacement of up to five litres were permitted to enter European Touring Car Championship races in future. AMG sold its racing saloon to the French Matra group, where it was converted for high-speed tests on aircraft tyres. Its subsequent fate is unknown. In spring 2006 Mercedes-AMG built a replica of the 300 SEL 6.8 AMG according to the original drawings, so as to keep this unique success story alive.